جستجوی مقالات مرتبط با کلیدواژه « پنیر سفید آب نمکی » در نشریات گروه « صنایع غذایی »

Cheese ripening is a complicated process that involves the breakdown of the cheese compounds via proteolysis, lipolysis and other enzyme catalysis which cause typical changes in cheese flavour characteristics. Lipolysis is one of the most biochemical reactions in cheese that through formation of short- and middle-chain fatty acids and finally convert them to flavour compounds such as methyl ketones, lactones, secondary alcohols, aldehydes and thioesters, plays an important role in cheese flavour and it also accelerate cheese ripening. Consequently, to increase cheese lipolysis in some cheese varieties, commercial lipases (with animal and microbial origins) is used. However, excessive levels of lipolysis may cause undesirable effect in cheese flavour and result in cheese rancidity. There is scarce investigation regarding to application of lipase enzymes (particularly animal lipases) in white brined cheese. Therefore, this research was performed to evaluate the effect of calf and kid goat lipases on development of lipolysis in Iranian-white brined cheese and to determine the best kind (calf or kid goat lipase) and appropriate level of enzyme to produce a cheese with an acceptable quality. In this research, Iranian-white brined cheese samples were produced from fresh cow milk via enzymatic (rennet cheese) procedure according to conventional method of cheese making in Iran. After standardization of milk fat to 3%, homogenization and pasteurization, the milk was cold to 35 ˚C and the calf or kid goat lipases at levels of 0 (control sample), 1.5, 3, 4.5 and 6 g/100 Kg of milk before renneting stage were added to the milk. The extent of free fatty acids/lipolysis (acid value, AV) and sensory scores (odour, colour, taste and texture) of Iranian-white brined cheese samples were measured during 90 days of the storage (1, 7, 14 and 21 days) at refrigerator and free fatty acid profile (FAP) analysis and microstructure assessment of cheese samples were measured at the end of 90 days of the cold storage. Analysis of fatty acid composition was carried out by gas chromatography with flame ionization detector. The results showed that increasing the amount of lipase concentrations and storage time significantly caused an increase in cheese lipolysis (p<0.01). Even though kid goat lipase introduced more changes in the experimental parameters like fatty acid profile and ADV, the kind of lipases had no significant effect on sensory attributes of the cheese samples (p>0.05). Furthermore, based on FAP results, though an increase in enzyme concentration produced a higher low-, medium-, long-chain and total free fatty acids (TFFA) (p<0.01), this increase was more obvious for low-chain fatty acids. Among different treatments, control sample with 132.91 g/100 Kg TFFA had the lowest and cheese sample containing 6 g kid goat lipase with 309.51 g/100 Kg had the highest TFFA at end of the 90-day storage period. Sensory evaluation also showed that samples having lipase enzymes had a higher mean sensory scores for odour, taste and texture when compared with control (without lipase enzyme) (p<0.001). Microstructure results of white brined cheese samples showed that by enzymatic treatment, an extensive lipolysis was occurred which subsequently caused a significant reduction in number and size of fat globules in the cheese structure. These changes due to formation of new cross-linkages between caseins and casein network rearrangement, result in a condensed texture and an increase in cheese hardness. According to the results, by using 4.5 g lipase enzyme (kid goat or calf, per 100 Kg of milk), a white brined cheese with improved sensory characteristics could be produced. Based on sensory results, no significant difference were found between two lipase enzymes, i.e. kid goat or calf lipases.

There have been great efforts to find safe and potent natural antioxidants from various plant sources. Due to the side effects of chemical preservatives and as a support of the idea for consumption of green natural food, demand for studies on the antimicrobial properties of natural preservatives and essential oils on the important food borne pathogens in vitro and in food products has been increased. Medicinal plants are complex natural mixtures which contain compounds at quite different concentrations, and their antioxidant activities are due to many substances including some vitamins, flavonoids, terpenoids, carotenoids, phytoestrogens, minerals, etc. Essential oils existed in some herbs or their antioxidant components as preservative agents in food makes them to be proposed as potential substitutes of synthetic antioxidants in food stuff.  Antioxidants are also widely used as additives in fats and oils and in food processing to prevent or delay spoilage of foods regarding to the harmful effects of synthetic preservatives on consumers’ health, there is an increasing attention, both in food industry and authorities, to medicinal and aromatic plants as natural preservatives in food products. White brined cheese is a kind of hard cheese which is produced from raw milk of cow, lamb and the main characteristics of the taste are pickling and salinity. White cheese, salt water, including products that may be at the time of manufacture or during storage by microorganisms such as Listeria. The objective of the present study was to investigate physicochemical properties, anti-microbial and sensory properties of frankincense essential oil and shallot oil in white brined cheese.

The whole treatments in this research were included: T0 (control), T1 (0.5% (w/w%) Frankincense and 0% shallots essential oil), T2 (0.6% (w/w%) Frankincense and 0% shallots essential oil), T3 (0.7% (w/w%) Frankincense and 0% shallots essential oil), T4 (0% Frankincense and 0.05% (w/w%) shallots essential oil), T5 (0% Frankincense and 0.1% (w/w%) shallots essential oil), T6 (0% Frankincense and 0.2% (w/w%) shallots essential oil), T7 (0.6% Frankincense and 0.1% (w/w%) shallots essential oil). In order to produce a white brine cheese, in the first step, the raw milk was pasteurized at 72 ºC for 15 seconds and cooled at 35ºC, then 5 liters of milk were poured into each of the sterile specialty dishes. Then, Listeria monocytogenes (103 cfu / ml) were then inoculated into milk samples. In the next step frankincense essential oil concentrations (0.5%, 0.1%, 0.6%) and shallot oil concentrations (0.05%, 0.1%, 0.2%) and mixture (0.1%+ 0.6%) were added. Then 0.02% (w/v) calcium chloride was added and after 0.5 % (w/w) of starter culture containing lycoplastic bacteria Lactobacillus bulgaricus and Streptococcus thermophiles were added into the milk samples and mixed. Finally, after the milk pH reached about 6.5, 0.001% (w/v) of microbial rennet was also added (Sanjiu Mito Japan Co.) After dissolving it, sterile water was added into the milk at 35 °C and 8 minutes for milk coagulation resting time was given. After coagulation (60 min), the cheese samples were cut into 1-2 cm slices and wrapped in a cloth to be kept in room temperature for 6 hours under 12 kg weight plates for dewatering. Coagulants were impregnated in 20% (w/v) salt water for 6-8 hours after cheese samples were cut while transferring to 8% salt water at 12-14 ° C for 15 days. Therefore, samples after the initial arrival time to arrive at the final arrival were kept at 4 ° C for 60 days (ISIRI NO. 5772, 2001). The essential oils chemical composition were determined by gas chromatography equipped with mass spectroscopy (GC/MS). GC-MS analysis of the essential oil was performed using Agilent-Technologies 6890N. Physicochemical, microbial and sensory properties of samples immediately on days 1, 30, 60 were measured but protein and fat on day 1after produced were measured.  Total protein was determined by macro kjeldahl method with national standard No. 1811 (Anonymous, 1383). Fat was determined by Gerber's method with national standard No. 8587. pH was determined by a MA-Mettler pH-meter and titratable acidity (percentage of lactic acid) was determined by 0.1 normal and phenolphthalein as identifiers using national standard No. 2852 (Anonymous, 1385). Level of moisture was determined by national standard No. 1753 (Anonymous, 1381). Salt percentage was determined by Moher method with national standard No. 1809 (Anonymous, 1356). To measure the number of Listeria monocytogenes, the microorganisms were measured in Palcam Agar Surface cultivation method at 30ºC for 72 hours (Khosravi and Malekan, 2004). Sensory analysis was performed by 10 trained panelists using a five point hedonic method with scales of one (very good), two (good), three (average), four (bad), and five (very bad) for taste, smell, texture, and overall acceptability with national standard No. 3442 (Anonymous, 1387). In order to design the treatments, a completely randomized design with factorial arrangement was used. For data comparison, Duncan's test was used at 95% confidence level. Minitab 16 software was used to analyze the statistical data.

The results showed that the antimicrobial essential oils of the highest possible antimicrobial against Listeria monocytogenes was shallots average number of bacterial treatments 0.2% essential oil shallots (T5) and 0.7% Frankincense essential oil (T3) at the end of the maintenance period cheese was 0.147 ×102 cfu/ml and 0.000 cfu/ml, respectively, when compared with other treatments maximum reduction showed (p≤0.05). Sensory evaluation results showed that the control cheeses had the highest sensory acceptability. Given that treatment with 0.2 shallot oil had the highest germicidal effect and organoleptic properties statistically significant difference between treatment and control samples were not mentioned. Therefore, the use of essential oils 0.2% in the formulation of white cheese shallot salt water in order to prevent the growth of Listeria monocytogenes is recommended and the treatment was selected as the best treatment.

Due to the side effects of chemical preservatives and as a support of the idea for consumption of green natural food، demand for studies on the antimicrobial properties of natural preservatives and essential oils on the important food borne pathogens in vitro and in food products has been increased. The goals of the present study included determination of biochemical properties and antimicrobial effects of Allium ascalonicum and Pimpinella anisum essential oils against Listeria monocytogenes in different steps of the ripening White Brined cheese. Results showed that 15 different substances made up 97. 2% of its content for Pimpinella anisum essential oil; Longifolene and Benzene had the highest concentrations among these 15 substances; Allium ascalonicum essential oil contained 15 different substances made up 96. 62% of its content; organosulfur substances had the highest concentrations among these 15 substances. The results of antimicrobial studies of these essential oils in the administered concentrations (Allium ascalonicum: 0، 0. 025، 0. 05، 0. 1 % and Pimpinella anisum: 0، 0. 05، 0. 1، 0. 2 %) during different steps of production and ripening of Feta cheese showed that Allium ascalonicum essential oils had the highest antimicrobial effects against Listeria monocytogenes. Treatments of 0. 1% Allium ascalonicum and 0. 2% Pimpinella anisum essential oils at the end of cheese ripening period showed the highest decrease in the mean bacterial colony counts (including 3. 79 and 4. 65 Log CFU/g، respectively) compared to other treatments (P< 0. 05). The results demonstrated that 0. 025% Allium ascalonicum essential oil maintained the highest acceptable range in cheese organoleptic assessment.